<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 120px;
            height: 120px;
            border: 1px solid black;
        }
        span {
            width: 20px;
            height: 20px;
            display: inline-block;
            border-radius: 50%;
            background-color: red;
        }

        .one {
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .two {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: space-around;
        }

        .three {
            display: flex;
            justify-content: space-around;
            align-items: center;
        }
        .three span:nth-child(1) {
            align-self: flex-start;
        }
        .three span:nth-child(3) {
            align-self: flex-end;
        }

        .four {
            display: flex;
            flex-wrap: wrap;
            align-content: center;
            justify-content: center;
        }
        .four span {
            /* 让一行装不下第三个点即可 */
            margin: 20px;
        }
        .six {
            display: flex;
            flex-wrap: wrap;
            align-content: center;
            justify-content: center;
        }
        .six span {
            /* 让一行装不下第三个点即可 */
            margin: 20px;
        }
        /* 六点与四点同理 */
        /* 以上1、2、3、4、6点都是用相似的html结构实现的：div里直接放span */
        /* 五点的话这个结构就比较不合适了，简简单单三个盒子，上下盒子里放两个点，中间盒子一个点最终实现五点 */
    </style>
</head>
<body>
    <div class="one">
        <span></span>
    </div>
    <div class="two">
        <span></span>
        <span></span>
    </div>
    <div class="three">
        <span></span>
        <span></span>
        <span></span>
    </div>
    <div class="four">
        <span></span>
        <span></span>
        <span></span>
        <span></span>
    </div>
    <div class="five">
        <span></span>
        <span></span>
        <span></span>
        <span></span>
        <span></span>
    </div>
    <div class="six">
        <span></span>
        <span></span>
        <span></span>
        <span></span>
        <span></span>
        <span></span>
    </div>
</body>
</html>